Seeinstructions): The underlying philosophy of the Core remains a belief that validation of diagnosis is critical to clinical research into neurodegenerative diseases and that tissue-based studies are a critical complement to in vitro studies of the biologic process that underlying these diseases. By providing these two pillars to the clinical and scientific community, the Neuropathology Core is able to make a contribution to the amelioration of suffering associated with AD and related disorders. The Specific Aims of the Neuropathology Coreare: 1. To establish an accurate neuropathological diagnosis on all brains submitted with standardized reporting, including clinicopathological correlation and interpretation of findings, to the Clinical Core, other treating physicians andfamilies; 2. To maintain a source of brain tissue and other samples for investigators studying AD and related disorders, through preparation of tissue in a standardized manner, including determination of RNAquality, with special consideration of investigators within the Massachusetts ADRC; 3. To work with the Clinical Core to develop, store and distribute DNA, cell lines, plasma and serum collected under the Clinical Core's Biomarkers Initiative; 4. To train diagnostic and experimental neuropathologists in the neuropathology of dementing disorders; and 5. To participate in cooperative ventures with other groups studying neurodegenerative diseases, both human and animal models, including other Alzheimer Centers (ADRCs &ADCs), NACC, NINDS- supported Udall Center, as well as other consortia and individual investigators. These broad goals, which are in continuity with the historical activities of the Neuropathology Core, will enhance the value of the collected brain tissue to individual investigators whose specific research projects depend upon receiving carefully prepared and examined tissue. RELEVANCE (See instructions): Brain tissue is a critical resource for many important experiments that are defining the underlying pathology of Alzheimer disease and other neurodegenerative diseases. The ability to use the collect tissue in experiments is essential as new therapies and disease markers are developed.